Multiplex photocell telemetering



3 Sheets-Sheet l Filed March 14, 1939 ROTATABLE DISC WITH ONE APERTURE 66 SYNCHRONOUS PHOTOELECTRIC TUBE PHOTOTUBE RELAY LINE PROTECTOR 76 /77 FULL WAVE RECTIFIER TIME DELAY RELAY n n n 89 V15 UAL 4 E RE 5 r LM H mm A v P n M n s m MM u s w m MW m M n MECHANICAL PHASE PHASE SHIFT ADJUSTER y mm: :h w nwc WWW e p um 0d 0 A R tn t 3 m d H mm me m 7 m mf o e y ma L 610 I 6 Z 9 1 9w G N I R E m L mm mm 5 mm Um m H P P I m March 5., 1 940.

3 Sheets-Sheet 2 Filed latch 14, 1939 Inventor George H.Llnder-hi|l,

Patentediviar. 5, 1940 MULTIPLEX PHOTOCELL TELEMETEBING George H. Under-hill, Ponghkeepsie, N. Y., assignor to General Electric Company, a corporation of New York Application March 14,

6 Claims.

My invention relates to remote indicating and registering devices and concerns particularly apparatus for transmitting a plurality of indications or measurements over a single circuit or channel.

It is an object of my invention to produce a multiplex telemeter in which the use of rotating contacts is unnecessary.

It is also an object of my invention to produce a simplified, reliable operating system for indicating measurements at a distance.

Another object of my invention is to provide an impulse teiemetering mechanism capable of operating at any desired speed.

It is still another object of my invention to provide remote indicating telemetering or supervisory systems in which the synchronization and phase relation of the impulses at the transmitting and receiving stations may be readily observed.

go checked, and corrected, and in which lack of synchronization or phase coincidence may cause an alarm which shuts'down the apparatus automatically, or which may be utilized to restore phase coincidence automatically.

It is a further object of my invention to produce a telemetering system capableyoi utilizing any communication channel.

Other and further objects and advantages will become apparent as the description proceeds.

form I utilize light sources intermittently illuminated at impulse rates corresponding to the magnitudes of measurements to be transmitted, together with photoelectric relays for converting the light flashes into electric impulses. Synchronously rotating disks are utilized at the transmitting and receiving stations for causing light responsive relays at the receiving station to be illuminated selectively in rotation in accordance with the energization of the lamps at the transmitting station by separate measuring devices. An additional lamp is provided at the transmitting station for synchronization purposes and a viewing screen is provided at the receiving station for observing the angular position of the flashes produced by the synchroniza-,

tion lamp in orderto determine whether or not the transmitting and receiving stations are synchronized. A mechanical phase shifter is provided at the receiving station for making any necessary corrections and an additional light responsive relay is provided at the receiving station for giving an alarm or for shutting down the apparatus or for correcting the phase adjustment in case the receiving station falls out of step.

In carrying out my invention in its preferred 1939, Serial No. 261,733

The invention will be understood more readily from the following detailed description when considered in connection with the accompanying drawings and those features of the invention which are believed to be novel and patentable 6 will be pointed out in the claims appended hereto. In the drawings Figure 1 is a circuit diagram schematically representing one embodiment of my invention; Figure 2 is an elevation partially in longitudinal section showing the apparatus at lo the transmitting station. Figure 3 is an end view 01' the apparatus shown in Figure 2. Figure 4 is an elevation partially in longitudinal section showing a portion of the apparatus at the receiving station, and Figure 5 is an end view par- 15 tially in cross section of the apparatus of Figure 4. Like reference characters are utilized throughout the drawings to designate like parts.

For the .sake of illustration I have shown in the drawings and have described hereinafter an em- 20 bodiment of my invention suitable for transmitting four diilerent indications over a single communication channel, although it will be understood that a considerably greater number of indications might be transmitted with the same as type of apparatus as that shown in the drawings. For the sake of simplicity and to avoid confusion in the drawings, however, apparatus for transmitting one of the indications only has been fully shown and many of the duplicate parts for transso mitting the remaining indications have been omitted from the drawings or have merely been indicated withouttheir connections being completed.

In the specific telemetering system illustrated, readings from integrating devices such as watthour meters are transmitted to a distance and may, if desired, also be caused to operate demand meters. The system may be used, for example, for transmitting the readings of watthour meters 0 and reactive energy meters connected in two diflerent circuits or for each direction of power how in the same circuit, thus making four different meters the readings of which are to be transmitted. To avoid unnecessary confusion in the drawings only one of such meters is shown at the transmitting station II and is represented schematically as a rotating disk integrating device Ii having a three-wire contact making device it mechanically connected to its shaft. A pair of lamps l3 and i4 is provided. They are so connected as to be energized alternately as the contact making device I! is operated by the meter II. A photoelectric device or tube It is provided which is adapted to be illuminated by the lamps l3 and II and shutter means in the term of a rotatable disk It having a single aperture is interposed between the lamps l3 and I4 and the phototube I5 so that light from only one lamp at a time falls upon the phototube IS. A transmission circuit is provided which may consist of a single telephone wire i1 constituting a telegraph channelof a communication system and the wire I1 is so connected as to have a current impulse transmitted thereover whenever the phototube i5 is illuminated (or is darkened).

At the receiving station l8 there is a lamp l9 which may be in the form of a neon tube ring or spiral and the lamp I9 is arranged to be controlled by the impulses transmitted over the communication wire i1. To correspond to the transmitting station lamps l3 and- N there is a pair I of photoelectric devices or tubes-20 and 2i at the receiving station. These phototubes are arranged to supply electric impulses whenever illuminated, to a distant dial, represented by its actuating coil 22, 'or'to any other desired apparatus which is operable by polarized or selective impulses, in order to reproduce the readings of the meter I l or to produce other indications dependent upon the readings or the rate of rotation of the meter H. A single-aperture rotating-disk snutter means 23 is provided at thereceiving station and is interposed between the neon ring I9 and the phototubes 20 and 2| so that only one of the phototubes is exposed to light'at any given time.

the minimum length of time that either lamp i3 or M remains illuminated in response to the greatest speed of operation within the range of the meter ii. Consequently, the light impulses supplied to the receiver phototubes 2d and 2B alternate at the same speed as the three-wire contact I? alternates the energization of the lamps i3 and i l. The apparatus controlled by the phototubes 20 and 2! may be of the well known type which advances only in response to alternately received impulses so that the action of the meter ii is accurately reproduced at the receiving station.

The remaining meters which may be provided at the transmitting station are not shown but for each of the additional meters there is a rotating contact device similar to the device 82 and a pair of lamps similar to lamps i3 and id arranged to be energized alternately in response to the rotation of the meter. For example, for the second meter, not shown, there is a pair of lamps 24 and 25, the connections of which have been omitted since they are similar to those of the lamps i3. and 14. For any additional meters there are additional pairs of lamps such as the lamps 26, 2i, 28 and 29 shown in Figure 3 but not 7 plained hereinafter. Corresponding to the lamps 24 and 25 for the second meter there is a pair of phototube's'3ll and 3| at the receiving station l8, and corresponding to the lamps 26 to 29. (Fig. 3) for the additional meters'there are additional phototubes such as the phototubes 32, 33, 34 and 35, as shown in Figure 5. The phototubes at the receiving station are also arranged around the periphery of a circle as shown in Figure 5 and a gap in the circle is left similar but not corresponding to the gap in the circle of lamps at the transmitting station, the angular positions of the corresponding lamps and phototubes being the same in order that the synchronously rotating single-aperture disks l6 and 23 will'permit light flashes initiated by the lamps at the transmitting station to be picked up by corresponding phototubes at the receiving station.

If desired, the readings of the meters, such as the meter II at the transmitting station, for various power circuits may be totalized at the receiving station by providing a totalizing relay 36 which is represented by showing its actuating coils which are of the alternately operatable type to respond to the alternating light impulses produced by the three-wire contact l2. If desired, a printing demand meter 3! may be provided which is so connected as to be controlled by the totalizing relay 36 and to print records of the total power demand of the circuits metered by the meters controlling the totalizing relay 36. desii-ed, an alarm-contact-operating demand meter '38 controlled by the totalizing relay 36 may also beprovided for giving an alarm when the demand of the combined circuits metered by the telemeterlng system exceeds a predetermined value. Of course, it will be seen that the same type of indications and controls maybe obtained In order that the synchronism of the disks l6:

and 23 may be checked to prevent indications in itiated by the wrong meter being picked up by the indicating dials at the receiving station, a pair of synchronizing lamps 39 and dd, is provided at the transmitting station It. As shown in Figure 3, the lamps 39 and 60 are-preferably spaced somewhat closer than'the remaining lamps and cocupy, but do not fully fill, the gap formed in the circle of lamps I3, l5, and ad to 29. For checking the synchronism a synchronism-checking viewing screen i! is provided at the receiving station and, as shown in Figure 5, occupies the gap in the circle of photoelectric tubes corresponding to that portion of the gap in the circle of lamps !3 to 29 occupied by lamps 39 and dd. The synchronism viewing screen di has an exposed area 32 corresponding in shape to a segment of an annulus, with two radially extending 'slot portions 63 and A l, having a radial dimension approximately equal to that of aperture hi in disk 23. The annular segment portion 62 is so positioned that light flashes produced by the neon ring is appear in the space M, and the notches 63 and at have the same angular positions as the.

synchronism checking lamps 35 and dd at the transmitting station. The lamps 89 and dd are continuously energ zed but cause light spots to be produced in the viewing screen M by virtue of the rotation of the single aperture disks id and 23 and the light spots will be at the angular position of, and will fill the-notches 63 and Q6 in the viewing screen 4! if the rotating disks are properly synchronized and have the same phase relation. If the h rotating disk at the receiving station should {all out of step the light flashes will either not be visible at all in the viewing screen 4| or will be displaced in position from the notches 43 and 44. For correcting this situation. a mechanical phase shifter 46 is provided whichpermits changing the angular relationshipbetween the disk 23 and the means for driving it.

' In order to guard against continued or resumed operation of the indicators at the receiving station after a severe voltage surge or a'voltage failure, an undervoltage relay 4'! is provided which stops operation of the indicators and gives an alarm in order that the adjustment of the apparatus may be checked to guard against improper indications. In order to guard against improper indications due to lack of synchronism or to improper phase'relationship between the rotating disks [6 and 23, a synchronism checking photoelectric tube 48 and a lock-outrelay 49 are provided at the receiving station. The synchronism checking phototube 48 is placed in the same circle with the other phototubes 20, 2| and 30 to 35 but in an angular positionnot occupied by any lamp in the circle at the transmitting station, sothat when the disks are in synchronism and in proper phase relation the s'ynchronism checking phototube 48 remains dark. However, in case the disks fall out of phase sufliciently to cause improper actuation of any phototube, one of the lamps l3, I4, 24 to 29, 39 or 40, will cause a light flash to be produced at the angular position of the synchronism checking phototube 48 to energize the same. In a manner which will be explained hereinafter the lock-out relay 49 is tripped by the phototube relay 96 and stops the operation of the indicating devices at the receiving station until the apparatus is restored to synchronism. An alarm bell .50 is provided which is energized in a manner to be described hereinafter in case of any improper occurrence such as an excess demand recorded by the demand meter 38, voltage surge or failure indicated by the unde'r-voltagerelay 41, or lack of synchronism indicated by the look-out relay 49, being operated by relay 88.

Considering the parts of the apparatus more in detail it will be seen that the meter H, the reading of which is to be transmitted, includes a rotating induction disk driven in a manner well understood to those skilled in the art at a speed proportional to the power traversing the circuit to which the meter H is connected. The three-wire contact l2, which is of a type well known to those skilled in the art, includes a rotating cam 52 connected directly or through gearl ing 53 to the rotating disk SI of the meter "H. The three-wlre contact l2 also includes a cam follower 54 carrying-a movable contact 55 cooperating with a second movable contact 58, which, is mechanically attached to a third movable contact 51 cooperating with a stationary contact 5! and as the cam follower 54 rises and falls with rotation of the cam 52, contact will be made alternately between the contacts 55 and it and between the contacts 51 and 68. Although I have referred to using a single-cam, three-wire contact, it will be understood that a double-cam, three-wire contact may also be used, in which there are two cam-operated movable contacts and one stationary contact cooperating with the movable contacts For the purpose of minimizing the load carriedby the three-wire contact i2, a pair of relays II and I may be provided which are energized by a source I and connect a current source 02 to the lamps l3 and I4 alternately as the two-circuit contact l2 changes from one position to the other.

In order to cause the rotatable disk IE to be driven at a substantially uniform speed corresponding to the speed of the disk at the receiving station, a synchronous motor 63 is provided with its shaft connected to the disk i6 and its windings connected to the alternating current source 62. Likewise at the receiving station, a synchronous motor 64 is provided having a mechanical connection to the rotatable disk 23 and having its windings connected to an alternating current source 65. It will be understood that the ultimate source of power for the alternating current sources 62 and 65 will either be the same or the systems will be interconnected in order that synchronism between the circuits and the rotating disks I6 and 23 can readily be maintained.

The disk 16 has been referred to as a single rotatable disk, but for the sake of greater effectiveness in shielding the phototube l5 against undesired light the disk It may actually be constructed in two parts, as shown in Figure 2,

with apertures 66 arranged along a line from the circumference of the circle of lamps to the phototube i5, and a stationaryv disk 51 may be provided with a plurality of apertures 88 at the angular positions of the lamps at the transmitting station. Preferably the lamps [3,. I4, 24 to 29, 39 and 40, at the transmitting station are placed in individual light-tight compartments which collectively form a light-tight box 59 of which the stationarydisk 61 forms the front surface. As shown in Figure 2, reduction gearing may be interposed between the synchronous motor 63 and the shaft 'll carrying the single aperture rotating disk IS. The arrangement may be such as to drive the disk It at any desired speed, there being practically no upward limit within the range of phototube response since rotating contacts are eliminated by the use of the phototube l5, but for transmitting meter readings I have found the speed of revolutions per minute to be satisfactory inasmuch as watthour' meters of the types now commercially used may be so designed that at their maximum speed a contact will be maintained for at least 12, seconds between one pair of contacts of the three-wire contact I2 before the circuit is broken and a contact will likewise be maintained for at least 12 seconds between the other pair of contacts of the three-wire contact l2 before the circuit is broken. The relays 59 and may, if. desired, be of the type customarily used in the telephone art. The lamps l3, i4, 24 to 29, 39 and 40 may conveniently be incandescent lamps of the usual commercial type.

Although I have shown the use of the telephone wire I! for transmitting the indications from the transmitting station ID to the receiving station [8 it will be understood that my invention is not limited to this precise arrangement and that any desired type of communication channel may be phototube II mm electrical impulses. a phototube relay I3 is provided which is energized by the transformer 12 and, in turn, energizes (or deenergizes) the telephone wire II in synchronism with the light impulses. For the purpose of re.-

- stricting the impulses to direct current impulses,

fee

to permit the use of a direct current relay at the receiving station, a full-wave copper oxide rectifler 14 may be interposed in the output circuit of the phototube relay I3, ground return being employed for completing the circuit of the telephone wire II. Although the arrangement may either be such that the communication channel I I is energized during periods when the lamps at the transmitting station are bright or such that 13 is preferably connected so that the communication channel I! is continuously energized except when light impulses are received by the phototube l5. This arrangement gives an immediate alarm in the event of communication channel failure and furthermore provides for an alarm in the event of a voltage surge at the transmitter of sufficient magnitude to affect the speed and thereby the phase angle of the motor 63. This 'alarm is accomplished by means of a quickopening, slow-closing time delay relay 15 which is arranged to open the supply circuit to rectifier 14 in the event of such a voltage surge and to reclose it only after a time delay of suflicient length to permit one complete revolution of disk 23 at the receiving station l8. During this revolution, the light source is remains lit continuously thereby operating the photocell 48, the relay 85, the relay 49 and the alarm bell 50. For protection of the line I! a line protector in the form of a resistor It may be employed, and a switch 11 may be provided for disconnecting the line i'l when the apparatus is not in use.

It will be understood that the phototube relay i3 is one of the type well known to those skilled in the art having an input power circuit 18 and output leads I9 betweenwhich a circuit is made and broken in response to illumination or darken--v ing or vice versa of the phototube l5, and the relay 13 need not, therefore, be described in detail.

At the receiving station, in order to obviate the necessity for carrying appreciable power on the telephone wire ii, a normally closed impulse relay 86, which may be a direct current relay, is proevided having contacts 8! which control the input from the alternating current power source 66 to motor 64 and the shaft 8 to which the single aperture rotating disk 23 is connected, and, in

order to permitvvarying'the phase relationshipv between the disk 28 and the synchronous driving motor 68, a mechanical phase shifter 46 is interposed between the reduction gearing 83 and the shaft 86. The mechanical phase shifter 65 may be of any desired type being shown as a planetary gear box with a rotatable housing which may be adjusted in angular position by means of a suitable handle 85. a

In order to prevent interference from stray light, the optical apparatus at the receiving station is also enclosed in a suitable light-tight hous ing. A stationary disk 86 is provided forming a front face of the light-tight-box enclosing the neon ring l9 and the rotating disk 23 The latter is preferably also divided into two parts each having a single aperture '1. The stationary disk I is'provided with a plurality of apertures 81' arranged around the periphery of the circle and corresponding in angular position to the photoelectric tubes 2|, 3| to 35 and 48. The opening 42 with the slois l3 and M which together form the synchronismviewlng screen ll is also cut into the stationary disk 86, and to permit observing the synchronism checking screen ll from the back of the apparatus, mirrors 88 and 89 are provided in a hood 9! in which an observation window 9! is formed to reflect an image of the opening 42 and slots 43 and M visible to an observer placing his eye at the window 9|. The

phototubes 20, 2|, to and 48 are preferably a three-wire direct current source 91 which, in

the particular embodiment illustrated, is shown as consisting of a neutral wire 98, a 62/ volt negative wire 99, and a 62% volt positive wire I00. Each pair of phototube relays corresponding to one of the pairs of lamps and to one of the meters at the transmitting station Ill is arranged to control both sides of the three-wire source 91 for operating a pair of coils of the totalizing relay 38. For example, the phototube relays t3 and 94, which correspond to the lamps i3 and it and the meter H at the transmitting station it, are connected with thei output terminals in circuit with the operating coils mi and 502 respectively of the totalizing relay 38, which is shown with three additional pairs of operating coils, the connections of which are not completed but which would actually be connected in circuit with additional pairs of phototube relays. If desired, an impedance box "33 may be provided for improving the tion with the wire 98 and with end terminals for connection across one of the pair of totalizing relay operating coils, such as the coils idi and I02. lhe neutral wire 98 is connected in series with normally closed contacts ltd of the lock-out relay is and the operating coil of the distant dial 22 to the mid or common terminal m5 of the pair of operating coils iiil and H32 of the totalizing relay 38. The negative side 99 of the direct current source 97 is connected to one of the outputterminals "it of the phototube relay 93 and the positive side I80 of the direct current source 9'! is connected to one of the output terminals ill! of the phototube relay 98. The other twooutput terminals its and "39 of the phototube relays 93 and 9d are connected to the outer ends of the totalizing relay operating windings it! and I02 respectively.

The distant dial, represented by its actuating coil 22, may be of .any desired known. type in which there is a register connected to a ratchet,

driven bye pawl carrying anarmature oscillated by an actuating coil r nsive only to impulses of alternately opposite polarity; I

The totalizing relay 38 may be of any desired type having pairs of alternately energizable operating windings, one pair ior impulses corresponding to each reading to be totalized, and also having a three-wire contact device I I for alternately changing connections from one lead III to another lead H2 at the rate of alternation corresponding to the total power-represented by the impulses supplied to the energizing windings. The three-wire contact I I0 is thus analogous in its effect on apparatus controlled thereby to the three-wire contact I2 which is customarily supplied with watthour meters which are intended to produce impulses at a rate corresponding to the magnitude of the power. The three-wire contact I I0 of the totalizing relay 38 includes also a movable contact I I3 which is brought into contact with one or the other ofthe leads III, H2. The totalizing relay 38 may, for example, be of the type described in pages 18 and 19 of the serial article entitled Metering of combined power and lighting circuits by E. J. Boland, originally published inthe General Electric Review for February, March and April 1932.

I1. it is desired to print records of the total power demand represented by the total power measured by the meters controlling the totalizing relay 38, a printing demand meter 31 may be provided, and if it is desired to obtain an alarm rectly connected to the three-wire contact device I2 of the meter II at the transmitting station.

Since the printing demand meter 31 may be of any desired construction and this apparatus in itself does not form a part of my invention it is not described or illustrated in detail. It may, if desired, be of the type illustrated in Patent No. 1,742,072 to Chester I. Hall and is represented as having a pair of operating coils H4 and H5 connected to the leads II I and H2 respectively of the three-wire contact device IIO of the totalizing relay 38, the mid connection II5 of the operating coils H4 and H5 being connected through the conductors II1, I I8 and H9 to the left-hand conductor of the alternating current circuit 55, and the movable contact II 3 of the three-wire contact device IIO of the totalizing relay 35 being connected through the conductor I to the right-hand conductor of the alternating current circuit 55. The printing demand meter 31 includes also an energizing coil I2I for the printing mechanism and a reset coil- I 22 for restoring a printing type wheel, not shown, to zero at the end of predetermined time intervals. There is a contact-making clock I23 which is associated with the printing demand meter 31, and includes a synchronous motor I24 energized by the alternating current source 85 for operating the clock and a pair of contacts I25 which are closed by the clock mechanism at predetermined intervals for connecting the coils I2I and I22 to the direct-current circuit 81.

The alarm-contact-operating demand meter 38 may also be of the type well known to those skilled in the art such as those described in United States Patents 1,710,681 Bean, and 1,603,- 051 Hall, and sold by the General Electric Company under the trade designation ems 10, for

.of the demand meter 31. The said movable arms of the demand meter 38 are so arranged that, in case the demand is excessive, the arm advanced by the energizing coils I21 and I28 overtakes the other arm and closes the pair of contacts I29, one of which is connected to the righthand conductor of the alternating current source 85 by the conductor I30 and the other of which is connected through the conductor I3I, an alarm bell transformer I32, and the conductor II9 to the other side of the alternating current source 85. The alarm bell 50 is connected on the output side of the transformer I32. For the purpose of stopping the ringing of the alarm bell due to excessive power demand a transfer switch I33 is provided having a normally closed contact I34 in the line I3I and having a normally opened contact I35 in series with an alarm indicating lamp I38 and the conductors IIS and I30 leading to the alternating current source 85. It will be understood, however, that I am not limited to 'long as adequate voltage is applied to the winding I 31; The contacts I38 thus form a hold-in circuit for the relay 41. The relay 41 is provided with a second pair of contacts I arranged to be closed'when the coil I31 is deenergized and, as will be explained hereinafter, the contacts I40 are connected to the energizing winding I of the look-out relay 48.

The lock-out relay 49 is of the electrically reset type having the normally closed contacts I04 adapted to be opened when the winding MI is energized and adapted then to remain open whether the winding I4I remains energized or not. The lock-out relay 49 also'has a pair of normally open contacts I42 and a resetting winding I43 which closes the contacts I04 and opens the contacts I 42 when it is energized. The normally open contacts I42 are connected between the conductor I30 on one side of the A. C. source 55 and a conductor I44 leading through the alarm operating transformer I32 to the conductor H9 and back to the other side of the alternating current source 55. V

The manual reset 45 includes a push-button I45 and a pair of normally open contacts I45, I41. The contacts I48 are connected between the conductor H9 of the A. C. source and the conductor I48 leading through the voltage alarm relay coil I31 back to the other conductor I30 of the A. C. source 55. The normally open contacts I41 of the manual reset 45 are connected between the conductor 8 or the A. C. source 85 and a conductor I48 leading through the look-out relay 7;

resetting coil its back to the other conductor oi the A. C. source 65.

In order to explain the operation of the apparatus, the cycle of events will be traced through for an operation of the three-wire contact device I2 driven by the meter II. When the meter II has measured an increment of electrical energy suflicient to cause rotation of the cam 52 an angular distance corresponding to the angular space of the cams, the cam follower 54 will change from one extreme position to the other, thus causing the lamp I3 to be illuminated and the lamp It to be extinguished through therelays 59 and 60. Since the single aperture rotating disk I6 makes at least one complete rotation within the time that the lamp I3 is illuminated, during this time a light impulse will be transmitted to the phototube I5 causing an interruption in the direct-current transmitted through the wire I1 and thereby deenergizing the normally closed relay 80 and producing a light flash oi the neon ring I9 during the period that the aperture 66 of the disk I5 is in front of the lamp I3. Since the disks I6 and 23 are synchronized, the photoelectric tube 20 will be exposed to the illumination of the neon ring I9 during the time that the lamp I3 at the transmitting station shines upon the photoelectric tube It. Accordingly, an electrical impulse will be supplied to the energizing coil of the distant dial 22 and to the operating coil I0! of the totalizing relay 36. If-

the 1amp I3 remains illuminated for a considerable period of time due to the slow operation of the meter II, additional light flashes will be produced as the aperture 66 of the disk I 6 again passes the lamp I3. However, there will be no eiiect upon the distant dial 22 since successivetact I2 to advance to a position extinguishing the lamp I3 and energizing the lamp I4, the next time the aperture 66 of the disk I 6 passes the lamp I4 the light impulse acting upon the phototube I5 produces a light flash of the neon ring I9 in the manner already explained and supplies a light impulse to the photoelectric tube 2| corresponding to the lamp It. Thereupon an electric impulse will pass through the distant dial 22 and the operating winding 3 I12 of the totalizing relay 36 causing the distant dial to be notched up a distance corresponding to the distance of rotation of the meter II and causing the arma-,

vancing this mechanism and causingalternate, operations of the three-wire contact Ht of the totalizing relay 3&3 depending in number upon the ratio between the input and output impulses for which the totalizing relay 3% is designed.

When the movable contact N3 of the t-wire the number of electric impulses received during tion of the check photoelectric tube 58.

amazes a predetermined time period, which, in turn, rep= resents the number of increments of electrical energy measured by the meter I I during the same time period, i. e., the power demand.

- In a similar manner the operating coils I2! and I28 of the demand meter 38 are operated and if the demand exceeds a predetermined value the contacts I29 are closed, closing the circuit through the alarm'bell 50. If the alarm transfer switch I33 is moved to the right the contacts I35 are closed and contacts I34 are opened, stopping the bell but connecting thelamp I38 through the lines H9 and I30 across the alternating-current source 65, thus lighting the lamp I36 to show that the cause for producing an'alarm has not been removed.

.The expression indicating device has been utilized in the claims to refer generally to devices of any kind for producing readings of or responses to measurements or indications, including registers, recorders and relays as well as deflecting-pointer types of devices.

In the foregoing discussion it has been as- .sumed that the single aperture rotating disks l5 determine whether or'not the lightpfiashes produced bythe neon ring I9 when the aperture 66 of the transmitter disk I6 passes the lamps 39 and 40 appear out of angular position with relation to the notches t3 and id in the viewing screen N. If the position of the light flashes does not coincide with the angular position of the notches 43 and 66, the phase angle is adjusted by rotating the handle 85 in one direction or another-to restore the phase relationship to the proper value. However, if the phase relationship alters more than a slight amount from the proper relationship the apparatus is shut down by the lock-out relay 49 in a manner which will i be explained hereinafter.

Normally the light flashes produced at the receiving station due to the lamps 3Q andfit at the transmitting station appear in the viewing screen 4| where there are no photoelectric tubes, and the light flashes produced by the other lamps at the transmitting station appear in the angular positions of the photoelectric tubes 2B, 2i

and ,30 to 35 but not in the angular position of the photoelectric tube =58. However. in case the disk 23 should fall even very slightly out of the proper phase relationship, the light flashes pro duced by lamps at the transmitting station will be changed enough in angular position so that one of these light flashes will appear in the postlight impulse directed to the photoelectric tube d8 will cause energization of the photoelectric relay Q3 which, in turn, will cause the winding Hit of the lock-out relay G9 to be energized thus One opening the contacts IQil and closing the contacts I52. The operation of the totalizing relay The closing of the contacts I52 causes energizetion of the alarm bell at, warning the operator atthe receiving station.

Aiter restoring the disks to synchronism and the proper phase relationship by means of manipulation of the handle in the manner previously explained, the operator operates the push button le of the manual reset switch 55 thus closing the contacts we and Mt. filosure or the contact it? energizes vthe resetting coil I 43 of the look-out relay 49, permitting the contacts I04 to close and the contacts I42 to open, and restoring the apparatus to. normal operation. In a similar manner, in case there has been a voltage failure the manual reset 5 closes the contact I46 to energize the winding i3! of the under-voltage relay 4? and permit simultaneous restoration of the look-out relay 48 to its normal operating position.

If desired a pair of constantly illuminated lamps i5l and I52 may be mounted close to, and on either side of, the normally dark spot in the transmitter stationary disk corresponding to the receiver tube 48 in order to provide for quick shut down (within one revolution) in the event of slight phase displacement instead of waiting, as would otherwise be the case, until one of the other lamps i3, 53, hi to 29, 39 or til happens to be illuminated during the time when the photocell 48 is exposed to the lamp i9 by the aperture inthe disk 23. i

If it should be desired to provide synchronization between the operation of the printing and reset coils of a demand meter located at the transmitting station with the operation of the printing and reset coils I2l and I22 of the demand meter 31 at the receiving station, both being actuated from a master clock located at one station, preferably at the transmitter, another lamp and photocell at the transmitting sta-' tion and another lamp and photocell at the receiving station may be provided for the purpose. Such synchronization may be accomplished'with out recourse to telemeter control where there is 60 cycle interconnection between the transmitter and receiver since the contact making clocks utilize synchronous motors.

Although I have explained apparatus in which phase error or lack of synchronism produces an alarm and the apparatus is corrected and reset manually it will be understood that my invention is not limited thereto but obviously includes apparatus in which the phase angle of the rotating disks may be corrected automatically by operation of the checking phototube 48. For example, an adjusting motor energized by the phototube relay 96 may be coupled to the handle 85 to correct phase angle, or ii two-way correction is desired, photocells arranged on either side of the viewing screen ll may be arranged to energize one or the other of two opposite-direction controlling windings of a reversible motor con nected to the adjusting handle 85. For obtaining both coarse and fine adjustment automatically an extra pair of coarse-adjustment checking phototubes may be provided beyond the first pair of photocells on either side thereof, and arranged to run the adjusting motor at high speed until synchronism is approached closely enough toilluminate one orthe other of the first pair of checking photocells or fine adjustment photocells. interlocks between the relays controlled by the coarse-adjustment photocells will preferably be provided so that the adjusting handle I! will be continuously driven in a given direction until proper phase angle is restored.

In case it is not possible to utilize synchronous or interconnected A. C. circuits for energizing the motors l3 and 64 and it is necessary to utilize a direct current motor at 64, a speed adjusting rheostat may be provided therefor which is driven by or in response to the said phase adjusting motor which may be connected to the handle 85.

It will be understood that the remaining op nected in a similar manner as the operating coils "ii and 592 in relation to the circuits of the remaining photoelectric relays, some of which are not shown in Fig. l, and that the operation of the additional lamps and photoelectric relays, the connections some of which are not shown, correspond to the operation of the lamps i3 and i4, photoelectric tubes 29 and ii and operating coils it)? and M2.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with the apparatus which I nowconsider to represent the best embodiment thereof but i desire to have it understood that the apparatus shown is only illustrative and that the invention carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A multiplex telemetering system comprising at a transmitting station a plurality of pairs of light sources, means for alternately energizing the light sources of each pair at a rate of alternation dependent upon one of a plurality of measurements to be transmitted, a light responsive relay, shutter means for normally shielding said relay from said light sources but for exposing said relay to each of said light sources in rotation during repeated cycles, the rate of repetition of said cycles of exposure being of a greater order of magnitude than the rate of alternation ofv illumination of said pairs of light sources for the largest measurements to be transmitted, and a source of energy, an energy transmission medium extending from the transmitting station to a receiving station and connected to said source oi energy under control of said light responsive relay, at a receiving-station a light source, means controlled by said energy transmission medium for intermittently energizing said receiving-station light source, a plurality of light responsive relays adapted to be illuminated by said light source, a second shutter means for normally shielding said latter mentioned relays from said receiver light source but for exposing each of said receiving station relays from said receiver light source in rotation during repeated cycles, a plurality of indicating devices, and means responsive to each of said pairs of receiver light-responsive relays for operating one 01" said indicating devices in response to the rate of energization of the corresponding pair of receiver light-responsive relays.

2. A multiplex telemetering system comprising at a transmitting station, a light responsive relay, means for subjecting said relay to a plurality of independently controlled light flashes in rotation during repeated cycles, each of said light flashes being produced intermittently at a. rate dependent upon the magnitude of a quantity to be telemetered, the rate of repetition of said' cycles being of a greater order of magnitude than the rate of flashing of said light flashes corresponding to the maximum value of any one of said quantities to be telemetered, an energy transmission medium controlled by said light responsive relay, at a receiving station a light source operatively connected to said energy transmission medium and adapted to be intermittently energized in response thereto, a plurality of receiver light responsive relays adapted to be illuminated by said receiver light source, means for causing said relays to be illuminated by said light source in rotation, and a plurality of indicating devices separately controlled by said light source and.

adapted to be energized thereby to produce readings dependent upon the rate of energization of said light responsive relays.

3. A telemetering system comprising at a transmission station, a light source adapted to become illuminated intermittently at a rate dependent upon the magnitude of the quantity to be telemetered, a light responsive relay, movable shutter means for intermittently exposing said relay to said light source, means for driving said shutter means at a substantially uniform speed, a transmission circuit controlled by said light responsive relay, at a, receiving station a light source operated by said transmission circuit for intermittently producing illumination of the latter light source at a rate corresponding to the rate of illumination of the first of said light sources, second and third light responsive relays, an indicating device responsive to the second of said light responsive relays adapted to be operated to produce indications dependent upon the rate of energization of said second light responsive relay, movable shutter means for intermittently exposing said second light source to said second relay, means for driving said second shutter means at a rate of speed substantially equalling the rate of the first mentioned shutter means, said second light responsive relay being located in such a position as normally to be exposed to light from the second source by the second shutter means when the first relayis exposed to light from the first source by the first shutter means,

means controlled by the third of said light responsive relays for producing a response in case of lack of phase coincidence of operation of said shutter means, said third light responsive relay being in a position normally kept dark by said shutter means but illuminated when said shutter means fall out of phase coincidence.

4. Atelemetering system comprising at a transmission station, a light source adapted to become illuminated intermittently at a rate dependent upon the magnitude of the quantity to be telemetered, a second light source and a light responsive relay, moving shutter means for intermittently exposing said relay to said. light sources in alternation, means for driving said shutter means at a substantially uniform speed, a transmission circuit controlled by said light responsive relay, at a receiving station a light source operated by said transmission circuit for intermittentlyproducing illumination of the latter light source at a rate corresponding to the rate of illumination of the first of said light'sources, a second light responsive relay, an indicating device responsive to the second of said light responsive relays adapted to be operated to produce indications meager dependent upon the rate of energization of said second light responsive relay, moving shutter means for said .second light source, means for station for observing the position of the light flashes produced in synchronism with the flashes of said first light responsive relay by said second light source at the transmitting station for the purpose of comparing the relative positions in the operating cycle at which said shutter means. expose said relays to the corresponding light sources, and means for shifting the'phase relation between the shutter means at the transmitting and receiving stations.

5. In a telemetering system a pair of photoelectric tubes adapted to be illuminated alternately at a rate depending upon the magnitude of a quantity to be telemetered, a three-wire source of direct current having a neutral conductor and positive and negative conductors, a relay having a pair of windings connected in series and adapted to be operated by application of current impulses to said windings alternately, a distant dial having an actuating coil adapted to advance the dial in response to current impulses of alternately opposite polarity, said actuating coil being connected between the common point of said relay windings and the neutral of said direct current source, and relay means controlled by said photoelectric tubes for connecting the remaining end of one or the other of said relay windings to the positive or the negative conductor of said direct current source in response to illumination of one or the other of said photoelectric tubes, respectively.

6. In a telemetering system in which pairs of impulses are transmitted at a rate depending upon the magnitude of a quantity to be telemetered, a three-wire source of direct current having a neutral conductor and positive and negative conductors, a relay having a pair of windings connected in series and adapted to be operated by application of current impulses to said windings alternately, a distant dial having an actuating coil adapted to advance the dial in response to current impulses oi alternately opposite polarity, said actuating coil being connected between the common point of said relay windingsand the neutral of said direct current source, and apparatus controlled by such transmitted impulses alternately for 'alternately'connecting the remaining end of one or the other of said relay windings to the positive or the negative conductor, respectively, of said direct current 

